The present invention relates to a zoom beam expander, and more particularly relates to an achromatic zoom beam expander which is particularly useful in laser chemical deposition tools.
U.S. Pat. No. 4,353,617 to Tokumitsu et al. for "Optical System Capable of Continuously Varying the Diameter of a Beam Spot" issued Oct. 12, 1982 and discloses an afocal zoom lens which continuously varies the diameter of a beam spot. The afocal zoom lens disclosed appears to be useful for only the red to infrared portion of the spectrum.
U.S. Pat. No. 4,461,546 to Muffoletto et al. for "Diffraction-Limited Achromatic Beam Expanding Telescope" issued July 24, 1984 and discloses a laser beam expander having four air-spaced all-spherical-surface lenses arranged in two pairs of Galilean telescope type series. The disclosed telescope is not a zoom lens, does not appear to be color corrected and requires adjustment for each change of wavelength.
U.S. Pat. No 3,609,006 to Pospisil issued July 8, 1971, U.S. Pat. No. 3,994,571 to Hirose issued Nov. 30, 1976, U.S. Pat. No. 4,372,654 to Fujioka et al. issued Feb. 8, 1983, U.S. Pat. No. 4,460,251 to Okudaira issued July 17, 1984, U.S. Pat. No. 4,466,708 to Betensky issued Aug. 21, 1984, U.S. Pat. No. 4,523,226 to Fujii issued Nov. 18, 1986, and U.S. Pat. No. 4,836,662 to Ogata et al. issued June 6, 1989 are all directed to zoom lenses. None of these patents discloses a Galilean zoom beam expander.
U.S. Pat. No. 4,621,890 to Suzuki et al. for "Optical Apparatus Including Two Afocal Systems" issued Nov. 1, 1986 and discloses an optical apparatus for imaging light from a laser device into a spot shape. The disclosed apparatus does not include a zoom beam expander and is directed to providing an apparatus in which the amount of light at the spot will not be changed upon variations of the emitting angle in the laser.